diff --git a/macro.h b/macro.h
new file mode 100644
index 0000000..fae0ee1
--- /dev/null
+++ b/macro.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#define ARRSZ(arr) (sizeof(arr) / sizeof(*arr))
+
+#define SWAP(a, b, type) do {					\
+	type tmp;						\
+	tmp = a;						\
+	a = b;							\
+	b = tmp;						\
+} while(0)
+
+
+#define ARR_FOREACH(arr, item) \
+	for (item = arr; item != arr + ARRSZ(arr) *  sizeof(*item); item++)
+
diff --git a/util.c b/util.c
new file mode 100644
index 0000000..1514964
--- /dev/null
+++ b/util.c
@@ -0,0 +1,48 @@
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void *
+xmalloc(size_t sz)
+{
+	void *res;
+	res = malloc(sz);
+	if (sz != 0 && res == NULL) {
+		perror("malloc()");
+		exit(EXIT_FAILURE);
+	}
+	return res;
+
+}
+
+void*
+xrealloc(void *ptr, size_t size)
+{
+	void *res;
+
+	res = realloc(ptr, size);
+	if (size != 0 && res == NULL) {
+		perror("realloc()");
+		exit(EXIT_FAILURE);
+	}
+
+	return res;
+}
+
+void
+xfree(void *ptr)
+{
+	if (ptr)
+		free(ptr);
+}
+
+void
+xerror(int rc, char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+
+	exit(rc);
+}
+
diff --git a/util.h b/util.h
new file mode 100644
index 0000000..aa141f4
--- /dev/null
+++ b/util.h
@@ -0,0 +1,9 @@
+#pragma once
+
+void *xmalloc(size_t sz);
+
+void* xrealloc(void *ptr, size_t size);
+
+void xfree(void *ptr);
+
+void xerror(int rc, char *fmt, ...);